T1 - Alcohol Lamp 2020/09/16 Inspect the lamp before each use to - PowerPoint PPT Presentation

T1 - Alcohol Lamp 2020/09/16 ▪ Inspect the lamp before each use to make sure there are no cracks, chips or defects in the glass body. ▪ Adjust the wick height to about 3 mm from the top of the metal cap. ▪ Fill the lamp with denatured or 95% ethanol through a funnel to about 1/2 to 2/3 volume. ▪ Light the alcohol lamp using a match. ▪ Use the lamp only in an upright position. ▪ Keep all combustible materials (clothing, paper, books, chemicals, etc.) away from the lamp when in use. T1 Video on YouTube (Click) ▪ Never use book or other items to raise the alcohol lamp. ▪ Use windshield to block wind and do not use books. Do not tilt lamp to avoid alcohol leakage while heating. ▪ Adjust device upon heating to an appropriate height. ▪ After use, cap should be put on to insulate air and extinguish the flame instead of blow it out. If lamp will not be used for a long time, alcohol inside should be returned to storage bottle. ▪ If lamp is overturned and cause small fire, cover the fire quickly with a wet rag and do not remove the rag immediately while extinguished, or flame may ignite again. Use fire extinguisher instead if a big fire happens. Inform teacher as soon as possible in such emergency and after fire is extinguished, immediately open doors, windows and exhausts to expel alcohol vapor in lab. 1

T2 - Stirrer/Hot Plate-I T2 Video on YouTube (Click) Controls and Indicators of CORNING-420 Stirrer/Hot Plate : ◼ Power Indicator: Green light on when Stirrer/Hot plate is properly connected to input power. ◼ Stir Control Knob: Turn it all the way counterclockwise to turn off stirring function. Turn it clockwise to set desired stirring speed. ◼ Heat Control Knob: Turn it all the way counterclockwise to turn off heating function. Turn it clockwise to set desired heating temp. ◼ Hot Top Indicator: Illuminates when the temp. of the top is too hot to touch (greater than 60 o C). When heating top is more than 550 o C, Stirrer/Hot Plate will automatically power off and indicator starts to flash until the temperature is less than 60 o C . ◼ White ceramic heating top with loading capacity 34 kg. 2

T2 - Stirrer/Hot Plate-II ⚫ Connect Stirrer/Hot Plate to a grounded power outlet with correct voltage. Never leave a gap between plug and outlet, replace damaged power cord immediately. ⚫ Keep power cord away from white heating top to avoid burns and damaged. ⚫ Always wear safety goggle and other protective equipment to avoid spillage while operating Stirrer/Hot Plate. ⚫ Place vessel in the center of white top with appropriate stirring speed. If stirring bar jumps irregularly, turn off Stirrer/Hot Plate to adjust vessel’s positon, then restart. ⚫ Clean white top before and after use or when liquid spills. Use non-corrosive cleaning agents and do not immerse Stirrer/Hot Plate in water for cleaning. ⚫ Replace Stirrer/Hot Plate once white heating top is broken or scratched. ⚫ Never heat large amount of volatile, flammable materials (such as ether, acetone, n -hexane, etc.) directly by a Stirrer/Hot Plate. ⚫ Insulating objects such as aluminum foil, thick-walled glassware cannot be heat by a Stirrer/Hot plate. ⚫ Take out stirring bar in solution by a Teflon-coated magnetic rod, do not grab it by hand to avoid corrosive chemicals and burns. 3

T3 - Mercury Barometer-I T3 Video on YouTube (Click) 4

T3 - Mercury Barometer-II ⚫ Step 1: Zero adjust Rotate the Zero Adjusting Knob to adjust the top of the mercury reservoir just touching the tip of the Zeroing Peg . ⚫ Step 2: Read the height of mercury column by the vernier ➢ Adjust the height of the Movable Scale so that the bottom of the slide piece is just even with the top of the meniscus. ➢ Read the main scale on the right of vernier. As in Fig. T3-1, the bottom of slide piece indicates the height of mercury is between 76.1 cm and 76.2 cm. ➢ Read the movable scale on the left of vernier where the lines match up with the main scale, i.e. 6 (the percentile of measurement). Therefore, the atmospheric pressure reads 76.16 cm-Hg. ⚫ For more precisely measurement, one should refer to manual of barometer to make correction of temperature. 5

T4 - Collecting Gases over Water ◼ Collection of gases over water is used to collect slightly water-soluble or water-insoluble gases from chemical reaction. ◼ Water-insoluble gas is introduced into water of gas collection device and for its density of the gas is lower than that of the water, gas will rise to displace the water out. Oxygen (O 2 ), nitrogen (N 2 ) and hydrogen (H 2 ) can be collected by this T4 Video on YouTube (Click) method. ◼ For gases that are soluble in water, such as ammonia (NH 3 ), hydrogen chloride (HCl) … etc., they are not suitable to be collected by this method. Operation: ◼ Invert the test tube that filled with water into the tub of water. ➢ ➢ Place the rubber tube into the opening of test tube that displace the water out. ➢ When the gas bubbles start to emerge from the opening of test tube, take rubber tube out of the test tube. ➢ Stand the test tube upside down on table (opening pointed downward) or stop it with a rubber stopper. 6

T5 - Decantation T5 Video on YouTube (Click) ▪ Decantation is a simple method to separate solids and liquid. ▪ When specific gravity of the solid precipitate is greater than liquid, it settles to the bottom. ▪ While there is little solid remain suspended, it may be separated easily from the liquid by carefully pouring off the liquid. ▪ Stand the suspended solution by allowing the solid to settle to the bottom of the mixture. ▪ Use a glass rod to guide the liquid flow when pour off the liquid from the beaker slowly enough that the solid is not carried along. 7

T6 - Gravity Filtration ▪ Fold the filter paper to cone shape. Tear off a small piece at corner to stick better to the funnel. Properly position the paper in the funnel, and the filter paper should not over the edge of funnel. Figure T6-1 Folding a filter cone ▪ Use a ring clamp to support the glass funnel. The tip of the funnel should Glass rod guiding decantation touch the side of the vessel which receives the filtrate. Pour the solution to the paper and no more than 2/3 ▪ Use a glass rod to guide liquid, and pour volume of filter paper Funnel with the liquid onto the paper not on the filter paper Ring clamp glass. Iron stand ▪ Pour the solution into the filter until the Receiving vessel The tip of the funnel touches paper cone is no more than two-thirds the side of the receiving filled. Never fill the cone completely. vessel ▪ After filtration, use tweezers to clip the Figure T6-2 Setup of gravity filtration filter paper; do not use your hand. 8

T7 - Vacuum Filtration T7 Video on YouTube (Click) ▪ Fill up the water tank of circulating water aspirator with water; keep circulating flow. ▪ Fix safety trap flask and suction flask with extension clamp. ▪ A Büchner or Hirsch funnel is sealed to the filter flask by the rubber. ▪ Select a suitable unfolded piece of circular filter paper to cover the perforations of Büchner funnel or Hirsch funnel. ▪ Moisten the paper with small amount of solvent, and tightly sealed against the bottom by turning on the water aspirator and closing the 2-way valve to apply suction. ▪ Test the suction works, then pour the solution down to a glass rod aimed at the center of the filter paper. ▪ After filtration, open 2-way valve first, then turn off the power of water aspirator to avoid the water backflow to the safety trap bottle from water tank. ▪ Turn off the circulating flow; drain the water in the water tank. 9

T8 - Centrifugation T8 Video on YouTube (Click) ▪ Check the casing inside the machine is intact and clean. ▪ Use centrifuge tubes in centrifugation; do not use ordinary test tubes . ▪ Use an equal number of tubes or fill one with a counterbalancing solution. Place centrifuge tubes on opposite sides to keep balancing . ▪ Always close the centrifuge cover before you start the motor, and open it only after the assembly has stopped. ▪ Start the centrifuge from low speed to check if there is any malfunction, then speed it up. ▪ If there are unusual sounds or vibration, turn off the centrifuge immediately in order to check and fix up. ▪ There must be at least one person look after the centrifuge when in use. ▪ When centrifugation is completed, turn off the switch and allow the rotating centrifuge assembly to come to rest. Do not attempt to stop the rotation manually when the 10 centrifuge is still rotating at high speed.

T9 - Electronic Balance ◼ To maintain calibration, never move the balance. ◼ Do not overload the balance. Maximum load of an electronic balance in lab is usually 610 g. ◼ Check to see that the balance is level and Electronic Balance Analytical Balance clean before use. ( ± 0.01 g) ( ± 0.0001 g) Warm up the balance for 30 min before use. ◼ T9 Video on YouTube (Click) ◼ Put weighed object in the center of weighing pan. Read digital readout for mass. ◼ Use folded weighing paper, beaker or bottle as container while weighing. Do not put chemicals on the pan directly. Always allow an object that has been heated to return to room temperature ◼ before weighing it. ◼ Keep the balance and its case scrupulously clean. The balance area has a soft brush for this purpose. Do not invert balance upside down to avoid damage to the parts inside. ◼ Analytical balance is an instrument with high precision with maximum load of ◼ 210 g. Close its windshields while zeroing and weighing. 11